wp_set_comment_status – Error : Missing argument 2

Hello world

We can read in codex :

wp_set_comment_status
Runs when the status of a comment changes. Action function arguments: comment ID, status string indicating the new status (“delete”, “approve”, “spam”, “hold”).

But when I try

add_action('wp_set_comment_status', 'toto' );
function toto($comment_ID, $status) {
   //stuff
}

I get the error :
Warning: Missing argument 2 for toto()

And of course no error when just declaring toto() with only one argument.

So ? do you know how to use both of the two arguments for wp_set_comment_status action ?

Thanks in advance